The Cyrix 486DLC is pin compatible to the Intel i386DX. While the internals of the 486DLC are roughly equivalent to those in the i486SX, the bus interface is identical to that of the Intel 386DX, respectively to allow easy replacement of the Intel CPUs by the Cyrix chips. The overall execution speed is about same as with an i486SX, but if you add a matching Cyrix FPU, e.g. a Cyrix 83D87, the speed is about 50% faster than an i486DX running at the same frequency.
For more information on the Cyrix 486DLC/SLC processors please refer to Norbert Juffa's excellent DLC/SLC info summary and performance comparison.

Where is the 486 DLC2 -50 and the 486SLC2 -50? There was a turbo/upgrade card for the IBM PS/2 model 30/286. This IBM was a crap computer in standard guise. With the upgrage card raising the bar to 486 DLC2 -50 (but only running at 20MHz), the computer was still crap. Yes, the 486 DLC2 has the pin-for-pin out of a 386DX, and the brains/smarts of a 486SX2 inside. But with its 286 converted to 486, and its 10-clock doubled to 20-clock, the "real-world" MS-Windows apps. were only 10%-50% faster. Sure our benchmarking apps. agreed with the 8x (800%) boost, but those MS-apps. didn't run even 2x (200%) faster at all. So I say, once a "boat-anchor", always a boat-anchor. I read about the 486SLC2 -50 being a pin-for-pin out of a 386SX, with the brains of a 486SX2 inside, but never saw it implemented in any desktop computer, only the IBM laptops! The last of the last 386SX m/boards that I saw, were running the AMD386SX -40, with motherboard cache (8k). Since the AMD didn't have L1 cache, but the Cyrix/IBM did have L1 cache, why didn't they make no-name desktop m/boards with 25MHz clock for the SLC2 -50 chips???